An infrared sensor wired to the part of the brain that processes tactile information enables rats to ‘touch’ infrared light. The successful experiment indicates humans can sense any region of the electromagnetic spectrum when enhanced with a neuroprosthesis.
In the field of neuroprosthetic technologies the focus is mainly on restoring sensory abilities lost due to brain injury. But at Duke University, USA, they wanted to know if it was possible to enhance sensory perception beyond its natural p...

An infrared sensor wired to the part of the brain that processes tactile information enables rats to ‘touch’ infrared light. The successful experiment indicates humans can sense any region of the electromagnetic spectrum when enhanced with a neuroprosthesis.

In the field of neuroprosthetic technologies the focus is mainly on restoring sensory abilities lost due to brain injury. But at Duke University, USA, they wanted to know if it was possible to enhance sensory perception beyond its natural potential.

The research team led by neurobiologist Miguel Nicolelis set up an experiment to augment the perception of rats to include infrared light. Rats, like all mammals, are blind to infrared and they can’t sense the low-intensity thermal radiation from the weak IR light used in the trial.

Nicolelis and colleagues implanted microelectrodes in the rat’s somatosensory cortex – the area of the brain that processes touch input- and wired those to an IR-detector secured on the animals head. When the sensor detected infrared it sent an electrical signal to the brain.

Enhanced with the neuroprosthesis the rats were immediately able to detect the novel sensory input. After about a month of getting used to it, they could seamlessly integrate the new data source and act upon the information it provided them.

The experiment proofs that it is possible to expand the perceivable range of the electromagnetic spectrum with the aid of a brain machine interface.

And what works for rats probably works for humans too. We could hook up to any kind of sensor and acquire night or X-ray vision. "We could create devices sensitive to any physical energy," Nicolelis said in the press release. "It could be magnetic fields, radio waves, or ultrasound. We chose infrared initially because it didn't interfere with our electrophysiological recordings."

Another interesting outcome of the study is that the neuroprosthesis can be plugged in to a sensory area of the cortex without ‘hijacking’ the function the brain naturally performs.

The implant in the rats was coupled to the sensory area that normally processes the touch signals from the facial whiskers. In the beginning the rats would scratch their heads when the IR-detector communicated a positive reading. That means the rats interpreted the signal as touch. But after 30 days of wearing the neuroprosthesis they learned to distinguish between touch and infrared input.

"When we recorded signals from the touch cortex of these animals, we found that although the cells had begun responding to infrared light, they continued to respond to whisker touch. It was almost like the cortex was dividing itself evenly so that the neurons could process both types of information” Nicolelis said. Once the rats were able to process the information they would actively employ the sensor by moving their heads to find an IR light source.

The finding could help people who have lost one of their five senses as a result of brain damage. A person who has lost his ability to see can have his sight restored with the aid of a brain implant connected one of the other four sensory areas of the cortex.